Problem: Simplify the following expression: $z = \dfrac{-9t}{2} + \dfrac{-7t}{2}$
Explanation: Since the expressions have the same denominator we simply combine the numerators: $z = \dfrac{-9t - 7t}{2}$ Combine like terms: $z = \dfrac{-16t}{2}$ Simplify by dividing numerator and denominator by 2: $z = \dfrac{-8t}{1}$ $z = -8t$